Anti-pollution compressor control system

ABSTRACT

An anti-pollution control for compressors used in gas recovery operations. An electrical circuit responsive to changes in gas pressure operates a selector valve to return gases that might otherwise be expelled to the atmosphere from the unloaders of compressors to the gas recovery system storage tanks or lines. For continuously operating rotary compressors similar control components alternately establish a no-load bypass for system lines that avoids atmospheric exposure.

United States Patent 1191 Ambler June 18, 1974 [5 ANTI-POLLUTION COMPRESSOR 2,751,143 6/1956 Biehn 417/298 CONTROL SYSTEM 2,899,013 8/1959 Carter 1 137/569 X 3,181,549 5/1965 Perry,Jr. 137/563 X [76] Inventor: Theodore C- Ambler, 275 5. 3,449,911 6/1969 Schlossel 417/295 Minnesota Ave., Casper, Wyo. 82601 Primary ExaminerWilliam R. Cline [22] Filed; Jun 16, 1972 Attorney, Agent, or Firm-C. B. Messenger [21] App]. No; 263,583

[57] ABSTRACT 52 us. on 137/115, 137/563 137/569 a1"ti-Pollution control for mmpressors used in gas 417/303 recovery operations. An electrical circuit responsive [51] Int. Cl. F041) 23/00 to changes in gas Pressure operates a selector Valve [58] 1 1611161 Search 137/563, 569, 115; return gases that might Otherwise be expelled the 417/295 297 298 303, 220/85 VR atmosphere from the unloaders of compressors to the gas recovery system storage tanks or lines. For contin- [56] References Cited uouslyoperating rotary compressors similar control components alternately establish a no-load bypass for UNITED STATES PATENTS system lines that avoids atmospheric exposure. 1,689,352 10/1928 Maxon 1. 220/85 VR 1 2,458,933 1/1949 Dodson 137/115 5 Claims, 5 Drawing Figures PATENTEflJumnu I 1817265 sniu 032 PATENiEBJuu 18 1914 Mama ANTI-POLLUTION COMPRESSOR CONTROL SYSTEM BACKGROUND OF THE INVENTION In oil field operations it is often beneficial to establish a system for the recovery of the gas that might be produced by the wells. Further, when oil is collected in storage tanks at the well sites the natural vapor pressure of the product will cause the release of gas in the tanks which is collected for use for both economic and ecological reasons. If gas is produced by the well or collected in the oil storage tanks, however, a substantial effort must be made to avoid fire hazards related to the gas accumulations. Provisions also have to be made for the delivery or retention of the gas product so that a regulated pressure can be maintained in the oil storage tanks. Since the pressure within the oil storage tanks is dependent on many factors, inclusive of the quantity of oil and gas being produced by the well, the. gas being delivered to the point of sale, the vapor pressure of the gas in the oil product, atmospheric temperatures and pressures, etc., it has been found necessary to provide a complete pressure regulating and gas recharging system for most oil field installations where both gas and oil are to be handled as sale products. The pressure regulating and gas recharging components are usually used in conjunction with a compressorwhich operates to elevate the pressure of the gas being extracted from the tanks and delivered to a sales line.

In many installations improved economy in operation is obtained where the compressor runs continuously with unloaders being used to control the actual gas compressing operations thereof. The compressor then rotates under no-load conditions until it is necessary to extract or deliver a portion of the gas product. There is an inherent problem however in the previous operations of compressor systems. with this type of control, since there has previously been a discharge from the compressor unloaders as the compressor is changed between load and no-load cycles. The unloaders discharge a portion of the gas product itself, and accordingly present collection and pumping stations can be quite noxious due to this gas discharge condition.

In order to avoid pollution of the atmosphere and also to eliminate an inherent fire hazard identified with such unloader discharge, the present invention provides a system for the return of such gas product from the unloaders of reciprocating compressors back into the gas recovery storage system or lines. Alternate control installations are adaptable for use with rotary compressors as well in order to avoid atmospheric contamination while still preserving the benefits of a constantly driven conpressor.

SUMMARY OF THE INVENTION Briefly stated, the present invention provides an electrical circuit which is to be actuated by an extension component provided on a pressure operated diaphragm type regulator valve connected in a pressure regulated flow system. Movement of the regulator diaphragm causes a coincident movement of linkage components of the regulator and the actuation of an electrical. circuit which is interconnected to a solenoid controlled three-way valve. This valve is positioned in lines interconnected to the unloaders of a reciprocating compressor or to a no-load bypass used with rotary compressor installations. The solenoid valve for the reciprocating compressor installation operates to return any unloader discharge of gas product back to the storage tanks or lines of the total gas recovery system. The solenoid control valve for the rotary compressor type installation is positioned in the outlet or sales line from the compressor, and it operates to establish a through passage for the delivery of compressed gases when the gases are being delivered from the compressor outlet to a sales line, or alternately it interconnects such outlet to a no-load bypass circuit for returning gases that have been discharged from the outlet of the compressor back to the inlet thereof. With this system it is unnecessary to expose the inlet for the rotary compressor to atmospheric influences in order to establish and maintain a no-load condition for the compressor.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view showing embodiments of the invention as used in a gas recovery system using a reciprocating compressor,

FIG. 2 is a schematic diagram showing use of a further embodiment of the invention in connection with a rotary compressor powered gas delivery system,

FIG. 3 is a side elevation showing components of a vapor recovery control system,

FIG. 4 is a cross-sectional elevation showing the structure of a diaphragm operated gas regulator valve, and

FIG. 5 is a rear elevation showing further features of. the regulator of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 illustrates a vapor recovery system that is typical of installations used in connection with large oil field storage tanks. A vent valve 12 is mounted atop such tank 11 with the piping system for the vent valve being interconnected to a vapor line 13. Any gas collected within the tank 11 can then be delivered through the vapor line 13 to an outlet or sales line 14. Passage from the vapor line 13 to the sales. line 14 is normally controlled by a wet gas regulator valve 16 which includes a diaphragm powered linkage mechanism for opening and closing a valve. A regulator control line 17 interconnects the top of the storage tank 11 and the wet gas regulator 16 so that operation of this regulator is at least in part dependent on pressure influences within the oil storage tank 11. Usually a dry gas regulator valve 18 is also provided so that dry gas can be introduced into the tank at any time to repressurize the tank when tank pressures fall below atmospheric pressure. When dry gas is thus introduced through operation of regulator 18a pressure in excess of atmospheric can be maintained within the storage tank 11, and there will then be no tendency for air to be introduced in the tank for mixture with accumulating vapors. Any such intermixture of air and gas would, of course, causea serious fire or explosion hazard which must be avoided.

Typical operation of the system shown could include the opening of the wet gas regulator when pressure in the tank has built up to 1/ 10th of an inch of water above atmospheric. This pressure influence will be conveyed by the regulator control line 17 to the diaphragm chamber for the wet gas regulator 16. The associated valve will, accordingly, be opened and gas will be delivered by the line 14 to a compressor which will pull additional gas out of the storage tank. After sufficient wet gas has been pulled from the tank by action of the compressor, the pressure within the tank will be reduced, and eventually the wet gas regulator 16 will close the vapor delivery valve. If the pressure within the tank is reduced below atmospheric pressures either by action of the compressor or due to a change in outside temperatures and/or pressures, the dry gas regulator 18 will be opened, and supplementary dry gas can be introduced from the line 19 to repressure the tank. Cooperative use of the regulators 16 and 18 and their associated lines will control the delivery of gas to sales lines and also prevent the introduction of atmospheric air into the tank thereby reducing fire hazards and corrosion problems.

Many field installations already have systems similar to that presented in FIG. 3. The output line 14 for such systems may at such installations be connected to a reciprocating compressor or to a rotary compressor. As previously set forth, it is often advantageous to provide a compressor that will be driven at all times even though only intermittent load or gas pressurizing cycles are required. A constantly driven compressor installation may be less subject to control system difficulties, and the expense of elaborate starter equipment for the drive motor may be avoided. A constantly running compressor can likewise avoid the periodic overload electrical conditions that result where a compressor is started and stopped to initiate load or duty cycles. For reciprocating type compressors it is also advantageous if the duty cycle is not started or initiated when the compressor is under a full load. Unloader type control components are usually used to avoid such overload conditions by closing the compressor inlet when the gas product is not being compressed for delivery to a sales line.

Incorporation and use of the otherwise beneficial unloaders on compressors has heretofore given an undesirable air pollution result. The gas product which operates the unloaders and controls the action of the inlet valves for the compressor has previously been exhausted to atmosphere when a particular duty cycle for the compressor is completed.

The present invention provides additional components to be incorporated in a gas recovery system so that such pollution discharge can be avoided. The operation of a first embodiment of the invention is shown in FIG. 1, which presents a gas recovery system utilizing a constantly running reciprocating type compressor 21. In general the components used in this system are directly relateable to the components previously described in connection with FIG. 3. A storage tank or scrubber 31 may be connected to a pressurized dry gas line 39 and to a wet gas line 34. A regulator control line 37 interconnects the top of the tank 31 with a dry gas regulator 38 and to a wet gas regulator 36. One side of the diaphragm for such regulators is, accordingly, subjected to pressures within the regulator control line 37. When wet gas regulator 36 is operated, its associated valve 46 will be opened in the wet gas or sales inlet line 34, and gas will be delivered by a flex line 41 to the inlet side of the compressor 21. After the gas is pressurized it will be delivered past pressure and temperature sensors 42 and 43, respectively, to an outlet sales pipe 44. The pressure and temperature sensors 42 and 43 are interconnected to read-out components 45 and 47 on a control panel 48. A manometer 49 is likewise provided on such control panel for interconnection to the regulator control line 37 at a tap 51. The readings provided by the manometer tap 51 and by pressure and temperature sensors 42 and 43 may be used in conventional manner to shut down operation of the drive motor for the compressor at any time that non-standard values are observed.

For further understanding of the improved system presented in FIG. 1, reference is now made to the operation of the diaphragm operated regulator valves. A typical cross-section for any of the regulators 16, 18, 36 or 38 is shown in FIG. 4. In this illustration inlet 52 is provided for interconnection to regulator control line 37. A diaphragm 53 separates the interior of the case 54 into separate compartments. Compartment 55 is subjected to the gas pressures in control line 37 and when the pressure in the control line is increased, diaphragm 53 will be moved. Diaphragm rod 56 will likewise be moved. A toggle end 57 on the rod 56 is connected to a lever 58 which turns the shaft 59 and operates to open a flow passage 61 through the valve 46. When this valve is open, gas will be delivered by lines 34 and 41 to the compressor 21. When the gas pressure falls, operations will, of course, be reversed. The construction and operation of the regulator valve so far described is identical to that of similar valves now used in some gas recovery installations. In connection with the present invention the movement patterns of the diaphragm valve are used to actuate an electrical switch 66 which is connected to a solenoid valve. In keeping with the invention an extension 62 is added to toggle arm 57 for movement therewith. A plate 63 on such extension is then positioned for engagement with the actuator arm 64 of the microswitch 66. This microswitch 66 is positioned on the case 67 for the diaphragm valve 36, and it actually may be moved with such case to noninterfering positions when the valve components are to be serviced. The switch 66, as shown in FIG. 1, is connected by conductors 68 to a solenoid operated threeway valve 71 disposed in an auxiliary piping system which interconnects the dry gas supply line 39, the compressor unloaders 72 and the regulator control line 37. When the switch 66 is energized, the solenoid control valve 71 will be moved to its initial illustrated position, and the unloader line 73 will be interconnected to a return line 74 which is itself connected into regulator control line 37. This flow connection relieves the gas pressure on the unloaders, and the inlet valves of the compressor will be opened to return the compressor to a duty cycle. When the pressure within the tank 31 has been sufficiently reduced, the pressure in the regulator control line 37 will be reduced, and the diaphragm 53 of regulator 36 will move to a normal position. Switch 66 will be de-energized. When the switch 66 is deenergized, the solenoid operated three-way control valve 71 will be moved to an alternate position as shown by the inset illustration at 71A. In this mode unloader line 73 will be flow connected to a pressurized dry gas supply line 76, and the unloaders 72 will be pressurized thereby to close the inlet valves for the compressor and to return the compressor to its idle or no-load operating cycle. When pressurized gas is being relieved from the unloaders or added thereto, there is no escape of such gas to the atmosphere, and all pollution effects are thus avoided.

ln P16. 2 a separate embodiment of the invention is shown wherein the components of a gas recovery system and the components of this invention are used together with a continuously running rotary compressor 81. Here, as in the previous embodiment, a tank 31 is interconnected to a regulator control line 37 and a sales inlet line 34. The wet gas regulator 36 again controls a valve 46 which passes gas from line 34 to the compressor 81. When the compressor is operating in the load cycle, the gas passing therethrough and through the three-way control valve 91 will be delivered to the outlet sales pipe 44. The valve 91 will be in this gas delivery position as shown whenever the microswitch 66 is energized to activate a solenoid 92 controlling the valve 91. As in the previous installation, when the gas pressure in the regulator control line 37 drops, the regulator 36 will close the valve 46 and switch 66 will be deenergized. With the electrical control circuit de-energizing the solenoid control valve 91 will be moved to the alternate position as shown by the inset illustration at 91A. With this no-load flow arrangement a bypass circuit is established from the discharge 93 of the compressor 81 through the valve 91 and back through a bypass line 94 to the suction side 96 of the compressor. With the compressor working on an essentially open circuit, no substantial work will be done. With this flow arrangement it is not necessary to open the intake and/or discharge lines for the compressor to atmosphere to establish a no-load operational condition. lntermixture of air and gas is avoided to reduce fire hazards, and pollution of the atmosphere is again prevented.

' In either system the solenoid operated valve is used essentially to change the back pressures operative on the compressor or on components thereof. In the reciprocating compressor installation, pressure on the unloaders is relieved, while in the rotary compressor installation a larger type of solenoid operated valve isolates the compressor from the back pressure in the sales delivery line through establishment of the bypass circuit. A beneficial characteristic of either operation is involved in the fact that there is no polluting discharge when the compressor is returned to its no-load cycle.

I claim:

1. Apparatus for the prevention of fire hazards and atmosphere polluting discharges in connection with the operation of compressors used in gas recovery systems where pressures in the recovery system are variable and where flow through a delivery line is controlled by valve means the operational movement of which is regulated in accordance with pressure changes in the accumulated gases in said recovery system, comprising a compressor for use to pressurize gases from the delivery line being delivered for sale, a motor drive for said compressor, unloaders on said compressor actuated by pressurized gases of the recovery system whereby the compressor may be run constantly under load and noload conditions, an electrical circuit, a switch in said circuit and positioned for actuation by moving elements of said valve means, a solenoid operated multiposition valve connected in said electrical circuit and flow connected in a discharge line for said compressor unloaders, and conduit means further flow connecting said solenoid operated valve to a zone of said gas recovery system of lower pressure than the unloader actuating pressure whereby operation of said solenoid valve will alternately subject the unloaders of said compressor to the said actuating pressure or relieve the compressor therefrom without escape of said gases.

2.Structure as set forth in claim 1 wherein said valve means is a pressure operated diaphragm controlled valve.

3. Structure as set forth in claim 2 and further com prising a control rod for movement with the diaphragm of said valve means, and an extension element for said control rod with said switch positioned for actuation by said extension.

4. Structure as set forth in claim 3 wherein said solenoid operated valve is a three-way valve for selectively pressurizing or depressurizing the unloaders of said compressor.

5. Structure as set forth in claim 4 and further comprising a source for pressurized gas in said system for selective interconnection by said three-way control valve to the unloaders for said compressor. 

1. Apparatus for the prevention of fire hazards and atmosphere polluting discharges in connection with the operation of compressors used in gas recovery systems where pressures in the recovery system are variable and where flow through a delivery line is controlled by valve means the operational movement of which is regulated in accordance with pressure changes in the accumulated gases in said recovery system, comprising a compressor for use to pressurize gases from the delivery line being delivered for sale, a motor drive for said compressor, unloaders on said compressor actuated by pressurized gases of the recovery system whereby the compressor may be run constantly under load and no-load conditions, an electrical circuit, a switch in said circuit and positioned for actuation by moving elements of said valve means, a solenoid operated multiposition valve connected in said electrical circuit and flow connected in a discharge line for said compressor unloaders, and conduit means further flow connecting said solenoid operated valve to a zone of said gas recovery system of lower pressure than the unloader actuating pressure whereby operation of said solenoid valve will alternately subject the unloaders of said compressor to the said actuating pressure or relieve the compressor therefrom without escape of said gases.
 2. Structure as set forth in claim 1 wherein said valve means is a pressure operated diaphragm controlled valve.
 3. Structure as set forth in claim 2 and further comprising a control rod for movement with the diaphragm of said valve means, and an extension element for said control rod with said switch positioned for actuation by said extension.
 4. Structure as set forth in claim 3 wherein said solenoid operated valve is a three-way valve for selectively pressurizing or depressurizing the unloaders of said compressor.
 5. Structure as set forth in claim 4 and further comprising a source for pressurized gas in said system for selective interconnection by said three-way control valve to the unloaders for said compressor. 